In enclosures containing electrical equipment, such as circuit boards, switches and systems, an air flow is needed to help keep the operating temperatures at a desired level. One way of performing this function is to have a fan unit providing lower temperature fresh air to the components in the enclosure. The fresh air flow would be provided in a lower area and rises to the top due to the convection heating of the enclosure.
Current devices for removing the heated air from the enclosure include air exit openings at the upper ends of the enclosures. Additional devices for allowing air to exit the enclosures include air ramps. However, in the case of a fire, the existing air ramp provides no means of controlling the air flow to extinguish a fire in the enclosure.